It should be remarked that the notation defined above is slightly different from the standard [1]}, [2]}, [3]}.
In [1]}, [2]}, [3]}, the underlying graph of a tensegrity is always a simple graph and a sign function \(\sigma \)  allows to take value 0 to represent a bar (which cannot stretch or shrink).
In our modeling, a bar can be represented by parallel edges with opposite signs, and hence ours is essentially identical to the standard model in [1]}, [2]}, [3]}.
However, our unconventional notation using multigraphs turns out to be crucial in the development of a new combinatorial theory.
